/*
 * This code implements the BASE64 algorithm.
 * This code is in the public domain; do with it what you wish.
 *
 * @file base64.c
 * @brief This code implements the BASE64 algorithm
 * @author Matthieu Speder
 */

#include "stdlib.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include "base64.h"


static const char base64_digits[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 62, 0, 0, 0, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
		0, 0, 0, -1, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
		15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 0, 0, 26, 27,
		28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,
		46, 47, 48, 49, 50, 51, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

char *
BASE64Decode(const char* src) {
	int in_len = strlen(src);
	char* dest;
	char* result;

	if (in_len % 4) {
		/* Wrong base64 string length */
		return NULL;
	}
	result = dest = malloc(in_len / 4 * 3 + 1);
	if (NULL == result)
		return NULL; /* out of memory */
	while (*src) {
		char a = base64_digits[(unsigned char) *(src++)];
		char b = base64_digits[(unsigned char) *(src++)];
		char c = base64_digits[(unsigned char) *(src++)];
		char d = base64_digits[(unsigned char) *(src++)];
		*(dest++) = (a << 2) | ((b & 0x30) >> 4);
		if (c == (char) -1)
			break;
		*(dest++) = ((b & 0x0f) << 4) | ((c & 0x3c) >> 2);
		if (d == (char) -1)
			break;
		*(dest++) = ((c & 0x03) << 6) | d;
	}
	*dest = 0;
	return result;
}
